1. Field of the Invention
The present invention relates generally to a housing for use with a variable resistor and more particularly to a housing for use with a variable resistor which can be assembled very easily.
2. Description of the Prior Art
A conventional housing for a variable resistor is such, for example, as shown in FIGS. 1 and 2, in which it comprises a disc-shaped top panel 3 having a bearing portion 2 for rotatably supporting an upper portion of a rotary shaft 1, a cylindrical body 6 having a spiral groove 4 formed on its inner surface 6a for mounting a spiral resistance element 5, and a disc-shaped bottom panel 8 having a bearing 7 for rotatably supporting the lower end of the rotary shaft 1.
The rotary shaft 1 has fixed thereon an insulating cylindrical slide member 1a to be rotated therewith. A top 9 is provided with clearance from the outer surface of the slide member 1a and the inner surface 6a of the body 6 to be rotatable therewith and also slidable thereon in the lengthwise direction of the rotary shaft 1 white being guided by the spiral resistance element 5 by the cooperation of elongated projections 1b provided on the outer surface of the slide member 1a along its lengthwise direction and recesses 9a formed in the inner surface of the top 9 each engaging with the projection 1b. Between a slide plate 10 of a conductive material, mounted on one side surface of the slide member 1a along the axial direction of the shaft 1, and the resistance element 5, disposed is a spring 11 both ends of which make sliding contact with them, respectively (see FIG. 2). A contact 12 is provided at the lower end of the slide plate 10 and held in sliding contact with a circular conductive member 14 connected to an output terminal 13 (see FIG. 3). The spiral resistance element 5 is connected at both ends to a pair of input terminals 15 and 16, respectively (see FIG. 3).
By the way, since the top and bottom panels 3 and 8 and the resistance element mounting body 6, which make up the housing for the variable resistor, are fixed together by means of screws 19 and 20, as illustrated, the assembling of the housing is troublesome and the screws 19 and 20 are likely to get lost during maintenance and inspection of the variable resistor and, in addition, the subsequent reassembling is not easy.
FIG. 3 shows another prior art example of the housing of this kind, in which the top and bottom panels 3 and 8 and the resistance element mounting body 6 are fixed together, using a pair of bands 23 and 24 and screws 25 and 26. Also in this case, however, the assembling work is relatively cumbersome and the screws 25 and 26 are liable to be lost during maintenance and inspection of the variable resistor.